The present invention relates to an image processing apparatus such as a facsimile apparatus, and more particularly to an image processing apparatus with a control system for controlling a feed motor which feeds a recording sheet when image data that have been received or read are to be compressed.
As facsimile apparatus find widespread use, they are equipped with an increasing number of functions. For example, some facsimile apparatuses can transmit and receive image data of documents in fine and superfine high resolution modes, as well as in a low resolution standard mode. Further, these apparatuses can provide a copying function and a size reduction function.
In the superfine mode, an image reader of the facsimile apparatus reads image data at a resolution corresponding to a superfine line (400 dpi). In the fine mode, the image reader reads image data at a resolution corresponding to two superfine lines (i.e., 200 dpi).
When image data read by the image reader and stored in a memory are to be copied on a recording sheet at a preset size reduction percentage, some of the image data is eliminated in an auxiliary scanning direction and then the remaining data is recorded on the recording sheet.
For example, image data composed of first line data (A line image data), second line data (B line image data), third line data (C line image data), fourth line data (D line image data), fifth line data (E line image data), etc., which is read in a fine mode, is to be reduced to 60% of its original size. The B and D line image data are skipped when processing the line data read in the fine mode. The remaining line data are converted to superfine data (i.e., A1, A2, C1, C2, E1, E2, etc.,) and successively recorded by an image recorder on a recording sheet. Thus the data processing is done on the fine mode data.
The recording sheet is fed in the auxiliary scanning direction by a feed motor that comprises a stepping motor. The feed motor feeds the recording sheet a superfine pitch of about 65 .mu.m each time one set of line image data is recorded on the recording sheet by the image recorder. Thus the feed motor is energized for a predetermined time "t" when each line image data is recorded on the recording sheet, and remains de-energized for a predetermined time "3t" (i.e., three times the period t), when line data (i.e., two successive lines) are being skipped.
Consequently, the feed motor is energized at different intervals of time, with the recording sheet being fed intermittently. Due to the moment of inertia and the load imposed on the feed motor, the feed motor is apt to step out of control. When the feed motor steps out of control, the recording sheet is fed an inaccurate distance, resulting in a reduction in the quality of the image copied onto the recording sheet.
Further, the skipping of two successive superfine data lines results in an uneven representation of the original image being reduced, since some data is completely omitted, and thus a poor quality image is recorded on the recording sheet.